// Copyright (c) 2021 Weird Constructor <weirdconstructor@gmail.com>
// This is a part of HexoDSP. Released under (A)GPLv3 or any later.
// See README.md and COPYING for details.

use crate::nodes::{NodeAudioContext, NodeExecContext};
use crate::dsp::{NodeId, SAtom, ProcBuf, DspNode, LedPhaseVals};
use crate::dsp::{out, at, inp, denorm, denorm_offs}; //, inp, denorm, denorm_v, inp_dir, at};
use super::helpers::Trigger;

#[macro_export]
macro_rules! fa_sampl_dclick { ($formatter: expr, $v: expr, $denorm_v: expr) => { {
    let s =
        match ($v.round() as usize) {
            0  => "Off",
            1  => "On",
            _  => "?",
        };
    write!($formatter, "{}", s)
} } }

#[macro_export]
macro_rules! fa_sampl_pmode { ($formatter: expr, $v: expr, $denorm_v: expr) => { {
    let s =
        match ($v.round() as usize) {
            0  => "Loop",
            1  => "OneShot",
            _  => "?",
        };
    write!($formatter, "{}", s)
} } }

/// A simple amplifier
#[derive(Debug, Clone)]
pub struct Sampl {
    phase:          f64,
    srate:          f64,
    trig:           Trigger,
    is_playing:     bool,
    last_sample:    f32,
    decaying:       f32,
}

impl Sampl {
    pub fn new(_nid: &NodeId) -> Self {
        Self {
            phase:          0.0,
            srate:          44100.0,
            trig:           Trigger::new(),
            is_playing:     false,
            last_sample:    0.0,
            decaying:       0.0,
        }
    }
    pub const freq : &'static str =
        "Sampl freq\nPitch input for the sampler, giving the playback speed of the \
        sample.\nRange: (-1..1)\n";

    pub const trig : &'static str =
        "Sampl trig\nThe trigger input causes a resync of the playback phase \
         and triggers the playback if the 'pmode' is 'OneShot'";
    pub const offs : &'static str =
        "Sampl offs\nStart position offset.\nRange: (0..1)\n";
    pub const len  : &'static str =
        "Sampl len\nLength of the sample, after the offset has been applied.\nRange: (0..1)\n";
    pub const dcms   : &'static str =
        "Sampl dcms\nDeclick fade time in milliseconds.\nNot audio rate!\nRange: (0..1)\n";
    pub const det : &'static str =
        "Sin det\nDetune the oscillator in semitones and cents. \
         the input of this value is rounded to semitones on coarse input. \
         Fine input lets you detune in cents (rounded). \
         A signal sent to this port is not rounded.\n\
         Note: The signal input allows detuning over +- 10 octaves.\
         \n\nKnob Range: (-0.2 .. 0.2)\n\
             Signal Range: (-1.0 .. 1.0)\n";

    pub const sample : &'static str =
        "Sampl sample\nThe audio sample that is played back.\nRange: (-1..1)\n";

    pub const pmode : &'static str =
        "Sampl pmode\nThe playback mode of the sampler.\n\
        - 'Loop' constantly plays back the sample. You can reset/sync the phase \
        using the 'trig' input in this case.\n\
        - 'OneShot' plays back the sample if a trigger is received on 'trig' input.\n";
    pub const dclick : &'static str =
        "Sampl dclick\nIf this is enabled and the 'pmode' is 'OneShot' \
         this will enable short fade in and out ramps.\n\
         This if useful if you don't want to add an envelope just for \
         getting rid of the clicks if spos and epos are modulated.";

    pub const sig : &'static str =
        "Sampl sig\nSampler audio output\nRange: (-1..1)\n";

    pub const DESC : &'static str = r#""#;
    pub const HELP : &'static str = r#""#;
}

impl Sampl {
    #[inline]
    fn next_sample(&mut self, sr_factor: f64, speed: f64, sample_data: &[f32]) -> f32 {
        let sd_len = sample_data.len();
        if sd_len < 1 { return 0.0; }

        let i = self.phase.floor() as usize + sd_len;

        // Hermite interpolation, take from 
        // https://github.com/eric-wood/delay/blob/main/src/delay.rs#L52
        //
        // Thanks go to Eric Wood!
        //
        // For the interpolation code:
        // MIT License, Copyright (c) 2021 Eric Wood
        let xm1 = sample_data[(i - 1) % sd_len];
        let x0  = sample_data[i       % sd_len];
        let x1  = sample_data[(i + 1) % sd_len];
        let x2  = sample_data[(i + 2) % sd_len];

        let c     = (x1 - xm1) * 0.5;
        let v     = x0 - x1;
        let w     = c + v;
        let a     = w + v + (x2 - x0) * 0.5;
        let b_neg = w + a;

        let f = self.phase.fract();

        self.phase = (i % sd_len) as f64 + f + sr_factor * speed;

        let f = f as f32;

        (((a * f) - b_neg) * f + c) * f + x0
    }

    #[inline]
    fn play(&mut self, inputs: &[ProcBuf], nframes: usize,
            sample_data: &[f32], out: &mut ProcBuf, do_loop: bool,
            declick: bool)
    {
        let freq = inp::Sampl::freq(inputs);
        let trig = inp::Sampl::trig(inputs);
        let offs = inp::Sampl::offs(inputs);
        let len  = inp::Sampl::len(inputs);
        let dcms = inp::Sampl::dcms(inputs);
        let det  = inp::Sampl::det(inputs);

        let sample_srate = sample_data[0] as f64;
        let sample_data  = &sample_data[1..];
        let sr_factor    = sample_srate / self.srate;

        let ramp_time         = denorm::Sampl::dcms(dcms, 0) as f64 * self.srate;
        let ramp_sample_count = (ramp_time / 1000.0).ceil() as usize;
        let ramp_inc          = 1000.0 / ramp_time;

        let mut is_playing = self.is_playing;

        if do_loop {
            is_playing = true;
        }

        let mut prev_offs = -10.0;
        let mut prev_len  = -10.0;

        let mut start_idx     = 0;
        let mut end_idx_plus1 = sample_data.len();

        for frame in 0..nframes {
            let trig_val = denorm::Sampl::trig(trig, frame);
            let triggered = self.trig.check_trigger(trig_val);

            if triggered {
                self.phase = 0.0;
                self.decaying = self.last_sample;
                is_playing = true;
            }

            let s =
                if is_playing {
                    let freq =
                        denorm_offs::Sampl::freq(
                            freq, det.read(frame), frame);
                    let playback_speed = freq / 440.0;

                    let prev_phase = self.phase;

                    let sd_len = sample_data.len();

                    let cur_offs =
                        denorm::Sampl::offs(offs, frame).abs().min(0.999999)
                         as f64;
                    let recalc_end =
                        if prev_offs != cur_offs {
                            start_idx =
                                ((sd_len as f64 * cur_offs)
                                .floor() as usize).min(sd_len);
                            prev_offs = cur_offs;
                            true
                        } else {
                            false
                        };

                    let cur_len =
                         denorm::Sampl::len(len, frame).abs().min(0.999999)
                         as f64;
                    if recalc_end || prev_len != cur_len {
                        let remain_s_len = sd_len - start_idx;
                        end_idx_plus1 =
                            ((remain_s_len as f64 * cur_len)
                            .ceil() as usize).min(remain_s_len);
                        prev_len = cur_len;
                    }

                    let sample_slice =
                        &sample_data[start_idx..(start_idx + end_idx_plus1)];

                    // next_sample mutates self.phase, so we need the current phase
                    // that is used for looking up the sample from the audio data.
                    let sample_idx = self.phase.floor() as usize;

                    let mut s =
                        self.next_sample(
                            sr_factor,
                            playback_speed as f64,
                            sample_slice);

                    if declick {
                        let samples_to_end = sample_slice.len() - sample_idx;

                        let ramp_atten_factor =
                            if sample_idx < ramp_sample_count {
                                sample_idx as f64 * ramp_inc
                            } else if samples_to_end < ramp_sample_count {
                                samples_to_end as f64 * ramp_inc
                            } else {
                                1.0
                            };

                        s *= ramp_atten_factor as f32;
                    }

                    self.last_sample = s;
                    out.write(frame, s);

                    if !do_loop && prev_phase > self.phase {
                        // played past end => stop playing.
                        is_playing = false;
                    }

                    s
                } else {
                    0.0
                };

            let s =
                if !declick || self.decaying.abs() < 0.00001 {
                    self.decaying = 0.0;
                    s
                } else {
                    self.decaying *= 0.98;
                    (s + self.decaying).clamp(-1.0, 1.0)
                };

            self.last_sample = s;
            out.write(frame, s);
        }

        self.is_playing = is_playing;
    }

}

impl DspNode for Sampl {
    fn outputs() -> usize { 1 }

    fn set_sample_rate(&mut self, srate: f32) { self.srate = srate.into(); }
    fn reset(&mut self) {
        self.trig.reset();
    }

    #[inline]
    fn process<T: NodeAudioContext>(
        &mut self, ctx: &mut T, _ectx: &mut NodeExecContext,
        atoms: &[SAtom], _params: &[ProcBuf], inputs: &[ProcBuf],
        outputs: &mut [ProcBuf], ctx_vals: LedPhaseVals)
    {
        let sample = at::Sampl::sample(atoms);
        let pmode  = at::Sampl::pmode(atoms);
        let dclick = at::Sampl::dclick(atoms);
        let out    = out::Sampl::sig(outputs);

        if let SAtom::AudioSample((_, Some(sample_data))) = sample {
            // 3 is for sample-sample-rate and at least 2 audio samples.
            if sample_data.len() < 3 {
                for frame in 0..ctx.nframes() {
                    out.write(frame, 0.0);
                }
                self.last_sample = 0.0;
                return;
            }

            self.play(
                inputs,
                ctx.nframes(),
                &sample_data[..],
                out,
                pmode.i() == 0,
                dclick.i() == 1);
        } else {
            for frame in 0..ctx.nframes() {
                out.write(frame, 0.0);
            }
            self.last_sample = 0.0;
        }

        let last_frame = ctx.nframes() - 1;
        ctx_vals[0].set(out.read(last_frame));
    }
}